Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Trimethoxy(propyl)silane (CAS No. 1067-25-0) hydrolyses rapidly in contact with water (DT50 = 2.6 h, QSAR) to form the silanol hydrolysis product propylsilanetriol and the alcohol hydrolysis product methanol (CAS No. 67-56-1).

The ECHA guidance R.16 states that “for substances where hydrolytic DT50 is less than 12 h, environmental effects are likely to be attributed to the hydrolysis product rather than to the parent itself” (ECHA, 2016). The TGD (EC2003) and ECHA guidance R.16 (ECHA 2010) also suggests that in case the hydrolysis half-life is less than 12 h, the breakdown products, rather than the parent

substance, should be evaluated for aquatic toxicity.  

Thus, the environmental fate assessment in this dossier is based on the hydrolysis products propylsilanetriol and methanol rather than the parent substance.



Propylsilanetriol is highly soluble in water (1.0 E+06 mg/L, QSAR), not readily biodegradable and has a low predicted log Kow of -1.4 (QSAR), indicating a low potential for adsorption to organic matter in soil, sediment and sewage. Volatilization is not expected based on its low vapour pressure of 0.285 Pa (QSAR). Therefore, the potential for adsorption to soil and sediment is low and it is likely to preferentially partition to the water phase, including the interstitial compartment in sediments where it is expected to persist. However, bioaccumulation is not of concern.



Methanol is fully water miscible at ambient temperatures, does not undergo hydrolysis and is readily biodegradable. It is characterized by a low log Kow of -0.82 to -0.64 (measured). Volatilization is not a significant removal process from the aquatic compartment.



OECD SIDS, 2004. Methanol - SIDS Initial Assessment Report For SIAM 19, Berlin, Germany: UNEP Publications.